Resilient retaining means and combination



Sept], 1970 c. B. KREKELER 3,526,435

RESILIENT RETAINING MEANS AND COMBINATION Filed Dec. 20, 1967 2 Sheets-Sheet 1 46 44 lNVENTOR/S //l/ %@BYMyWTTO9%SM/% CLAUDE B. KREKELER,

Sept. 1,1970 0. B. KREKELER 3,526,435

RESILIENT RETAINING MEANS AND COMBINATION 2 Sheets-Sheet 2 Filed Dec 20, 1967 ATTORN EYS United States Patent 3,526,435 RESILIENT RETAINING MEANS AND COMBINATION Claude B. Krekeler, Hamilton County, Ohio, assignor to The Cincinnati Mine Machinery Co., Cincinnati, Ohio,

a corporation of Ohio Filed Dec. 20, 1967, Ser. No. 692,170 Int. Cl. E21c 25/46 US. Cl. 29992 19 Claims ABSTRACT OF THE DISCLOSURE A resilient retaining means for maintaining the shank of a cutter bit, for a mining machine and the like, in the shank receiving perforation of a socket member or lug. The retaining means comprises a body of resilient substance and an engagement element afiixed to the body. The engagement element has an engagement nose adapted to cooperate with a notch in the cutter bit shank. The retaining means is located in a transverse hole in the lug, the transverse hole and the shank receiving perforation being interconnected. The engagement nose is of a width less than the width of the shank receiving perforation and extends thereinto.

BACKGROUND OF THE INVENTION Field of invention The invention relates to a resilient retaining means and more particularly to a resilient retaining means for maintaining the shank of a cutter bit, for a mining machine or the like, inthe shank receiving perforation of a socket member or lug.

Description of the prior art In US. Letters Patent Nos. 2,965,365, 3,057,609 and 3,088,721 there is described a type of resilient retaining means for the cutter bits of mining machines or the like, and combinations of such resilient retaining means and socket members, hereinafter called lugs, such lugs having a perforation to receive the shank portions of a cutter bit. Broadly speaking, the resilient retaining member comprises a rigid rod such as a rod of metal extending substantially axially of what may be termed a cylindrical body of resilient substance. The lug has a hole which extends from side to side, and which intersects the shank receiving perforation. The resilient retainer is placed in the hole so that it passes across the perforation with portions extending beyond the perforation on either side. The body of resilient substance is so configured as to expose the internal rod within the perforation; and the hole is so spaced that at least about half of the rod projects into the perforation. The shank of the cutter bit is provided with a notch which is engaged by the rod of the resilient retaining device when the bit shank is fully home in the perforation; and the lower rear corner of the bit shank is relieved in such a way as to depress the rod during the initial stages of its insertion in the perforation, the rod remaining in the depressed position until it springs outwardly into the notch of the bit shank. Such resilient retainers may be provided with a cage element which not only prevents rotation of the retainer in the hole, but also limits the axial distortion of the body of resilient substance. A suitable type of bit for use with the described resilient retainers is shown in US. Letters Patent No. 3,114,537.

Since the rod is located substantially axially of the body of resilient substance, the extent of the deflection of the rod is limited by the quantity of resilient substance located essentially behind the rod; and thus the resilient Patented Sept. 1, 1970 retainers are preferably somewhat large in diameter. In accordance with the present invention, retainers are provided which, for given size, have a greater resilience because of the provision of a greater quantity of the resilient substance behind the bit shank engagement element thereof.

The present invention further contemplates a combination lug and resilient retainer structure in certain embodiments of which a bit engagement element projects laterally from the periphery of a body of resilient substance. In the use of such a retainer it is not necessary that the hole to receive the resilient retainer intersect the shank receiving perforation in the lug or intersect it to as great an extent as has been the case hitherto.

The resilient retaining means of the present invention is capable of being easily inserted in and withdrawn from the lug hole by a driving action, and in certain embodiments the resiliently mounted engagement means serves to fix the longitudinal position of the retaining means in its hole.

In accordance with the present invention, any movement of the bit shank engagement element, excepting a movement substantially normal to the axis of the perioration, is minimized. In addition, a structure for retaining means, enabling the production of simpler, smaller and cheaper types of elements than has been the case hitherto is provided.

SUMMARY OF THE INVENTION The resilient retainer of the present invention com prises a body of resilient material with an engagement element aflixed thereto. The engagement element has a nose portion. The resilient retainer is adapted to be received within a transverse hole in a lug member. The nose portion of the engagement element is adapted to extend into the shank receiving perforation of the lug. The nose cooperates with a notch in the shank of a cutter bit and maintains the cutter bit shank in fully seated position within the shank receiving perforation.

In certain embodiments of the resilient retainer, the engagement element comprises a nose portion, upper and lower face portions having substantially the same contour as the resilient body, and inturned marginal portions embedded in the resilient body.

In another embodiment, the nose portion of the engagement element comprises a central protuberance on an elongated member embedded in and extending the length of the resilient body. In yet another embodiment, the nose portion comprises an element having rearward tine portions at either end adapted to be embedded in the resilient body.

In the embodiments thus far described, when the resilient body is of a cylindrical configuration, it may he provided with an integral key adapted to be received in a keyway portion of the transverse hole. The key prevents rotation of the resilient body within the transverse hole in the lug. While the key may be located at any peripheral position on the resilient body, it will normally be located diametrically opposite the nose of the engagement element, or on the same side of the body as the engagement element and in alignment with it.

In all of the embodiments thus far described, the engagement element may be made by casting, or by stamping or forming operation from sheet metal.

In yet another embodiment, the resilient retainer may comprise a cylindrical resilient body having an inwardly extending depression located centrally of the long dimension of the body, there being an engagement element located in the depression. While the engagement element may be of any suitable type, it is preferably formed with a nose portion, upper and lower extended portions and rearwardly extending, bent over marginal portions adapted to be embedded in the resilient body. Again, all of the embodiments thus far described may be provided with a cage means, having a keyway and restricting permanent endwise distortion of the resilient body. In a final embodiment, a cylindrical body of resilient material may be sheathed in a cylindrical metallic casing having an integral key and a diametrically opposed, centrally located perforation. A plunger-like element is provided, having one end embedded in the resilient body, and the other end extending radially outwardly through the performation in the sheath and comprising the engagement nose. In all of the embodiments, the engagement nose may be so configured as to permit insertion and removal of the resilient retainer in the transverse hole by a driving action.

The invention further teaches the provision of lug members having suitably configured and suitably located retainer-receiving transverse holes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of one form of the resilient retainer of this invention.

FIG. 2 is a sectional view thereof taken along the section line 22 of FIG. 1.

FIG. 3 is an isometric view of a modified form of resilient retainer.

FIG. 4 is an isometric view of a further modification.

FIG. 5 is a sectional view of the structure of FIG. 4 taken along the section line 55 of that figure.

FIG. 6 is an isometric view showing a further modification of the structure of FIG. 2.

FIG. 7 is a front elevational view of a further modification of the resilient retainer of the present invention.

FIG. 8 is a cross sectional view taken along the section line 88 of FIG. 7.

FIG. 9 is an isometric view of yet another modification of the resilient retaining means.

FIG. 10 is a transverse sectional view taken along the section line 1010 of FIG. 9.

FIGS. 11 and 12 are transverse sectional views similar to FIG. 10 and show modified forms of engagement ele ments.

FIG. 13 is an isometric view of the resilient retainer of FIGS. 1 and 2 provided with a cage.

FIG. 14 is an isometric view of another embodiment of the resilient retainer of the present invention.

FIG. 15 is a cross sectional view taken along the section line 1515 of FIG. 14.

FIG. 16 is an isometric view of another embodiment of the resilient retainer of the present invention.

FIG. 17 is a sectional view taken along the section line 1717 of FIG. 16.

FIG. 18 is an isometric view of a cast engagement element of the type used in the embodiment of FIGS. 1 and 2.

FIG. 19 is a longitudinal section of one form of lug provided with a hole to receive the resilient retaining means of any of FIGS. 1-6, 13, 16 and 17.

FIG. 20 is a longitudinal sectional view of a lug adapted to receive the resilient retaining means of FIGS. 7 and 8.

FIG. 21 is a longitudinal sectional view of a lug adapted to receive the resilient retaining means of FIGS. 7 and 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the simplest forms of the present invention is illustrated in FIGS. 1 and 2. This form comprises a resilient body 1 of suitable, tough, resilient, elastic substance, generally made from natural or synthetic rubbers, chloroprenes, or other elastomers or mixtures thereof. The body of elastic and resilient substance may be provided with a longitudinally extending key 3. The key may be located at any suitable position on the periphery of 4 the body '1. In FIGS. 1 and 2 the key is shown as located along the rear side of the body.

An engagement element of rigid material, preferably metal, is generally indicated at 4. This engagement element has upper and lower face portions 6 and 7 having substantially the same contour as the body 1 and between which there is a nose portion 8 projecting from the general periphery of the resilient body. Reference to FIG. 2 Will indicate that the engagement element also has inturned marginal portions 9 and 10 on the edges of the portions 6 and 7. The structure is such that it can be conveniently made by stamping or forming operations from sheet metal. The length of the nose portion of the metal engagement element just described need not be greater than the width of the shank receiving perforation of the lug. When used with a lug provided with a hole to accept the resilient body 1, the hole having a keyway to accept the key 3, it will be possible to drive the resilient retainer into the hole, providing end portions of the nose 8 are chamfered or relieved as shown at 8a. In other words, the act of driving the resilient retainer into the hole in the lug will depress the engagement element against the resilience of the rubbery body 1. The length of the engagement nose being slightly less than the width of the shank receiving portion, the nose 8 will snap into position within the perforation when the resilient engagement means is in the proper position and will tend to hold the resilient engagement means against axial movement. The extent of end portions of the body 1 into end portions of the hole beyond the perforation may be only sufficient for stability and to close adjacent portions of the hole against the entry of fine cuttings and acid mine waters.

The nose 8 preferably has an external contour similar to the contour of the rod of the resilient engagement means of the above mentioned U.S. Letters Patent, but it may project outwardly from the surface portions 6 and 7 as far as desired. If the hole is so related to the perforation (as hereinafter more fully explained) that only the nose portion 8 projects into the perforation, it will be evident that the engagement means will be restrained from rotary movement or movement in any direction other than a direction normal to the axis of the perforation,

Another form of resilient retaining means is shown in FIG. 3. Here there is again a resilient body 1 which may have a key 3 formed integral therewith. A shank-engaging means 12 in this instance may extend for the full length of the resilient body and will have at its central portion a protuberance or nose 13. This protuberance is adapted to engage a notch in the shank of a cutting bit and hence has a length less than the width of the shank receiving perforation in the lug with which it will be used. End portions 14 and 15 of the protuberance or nose 13 are relieved as shown so that the engagement means will be self depressing as it is driven into a suitable hole in the lug, but will be held against endwise movement when the protuberance 13 lies within the shank receiving perfora tion of the lug. The nose 16 of the engagement element may be given any shape deemed suitable to coact with the notch in the bit shank.

Yet another modification is illustrated in FIGS. 4 and 5. Again the resilient body 1 may be provided with a key 3. A protuberance or nose 13, which is the shankengaging element, is shown extending from the mid-section of the body; and the various parts of it bearing similar index numerals may be shaped as hereinabove described. However, in this instance the engagement element does not extend for the full length of the resilient body. Instead, as shown in FIG. 5, tine-like portions 17 and 18 extend radially inwardly from the protuberance 13 and have bent over ends 19 and 20.

Where in this specification elements such as 9, 11 and 17-20 inclusive are shown extending into the rubbery body 1, it Will be understood by the skilled worker in the art that the rubbery substance may be molded in and around the inward extensions, although in some instances it may be possible so to shape the rigid engagement elements of this invention that inwardly extending portions thereof may be inserted in preformed openings in the rubbery body. Where this is done, the inwardly extending parts of the engagement elements may be adhesively secured to the rubbery body. Molding and vulcanizing the parts together will give a stronger structure.

The engagement elements illustrated in FIGS. 3, 4 and 5 may be made easily and cheaply by stamping from metallic plate-like material of suitable thickness and with or without bending.

FIG. 6 shows a modification of the structure of FIGS. 1 and 2, wherein the essential difference is that instead of forming a key 3 on the rubbery body itself, a rear backing element is provided. This element is preferably made from sheet metal so shaped as to provide a key 3a and outlying portions 21 and 22, which portions taken together provide a substantially semicircular configuration. Again the rubbery substance of the body 1 is preferably molded against the backing element and the backing element itself is preferably secured in place either adhesively or by vulcanization. Otherwise the structure is the same as has been described in connection with FIGS. 1 and 2; and it will be noted from a comparison of the latter of these figures and FIG. 6 that the inturned portions 9 and 11 are so disposed that they would not contact elements 21 and 22 of the backing.

The essential difference between the structure shown in FIGS. 7 and 8 and the structure shown in FIGS. 1 and 2 is that instead of forming a key on the rear surface of the resilient body 1, keys 23 and 24 are formed on the front surface of the body in alignment with the engaging nose 8. As hereinafter explained, the structure of FIGS. 7 and 8 may be used in a transverse hole in the lug, which hole has a forwardly extending keyway broached in connection with it. This makes it unnecessary to deflect or depress the engagement elements 4, 6, 7 and 8 to as great an extent in inserting the resilient retainer into the hole in the lug. It is within the scope of the invention, however, to make the key elements 23 and 24 on the body of somewhat lesser height than the engagement nose 8 so that some deflection of the engagement element will be required upon insertion of the retainer in the hole, and so that once the retainer has been fully inserted the engagement nose 8 will tend to prohibit longitudinal displacement of the retainer.

FIGS. 9-12 relate to a form of structure in which the resilient body 25 is of rectangular configuration. Referring to FIGS. 9 and 10, there is provided in connection with the rectangular body 25 an engagement element generally indicated at 26. The engagement element 26 has an engagement nose 27, the ends of which are relieved as is indicated at 28. The engagement element has upper and lower extensions 29 and 30, the ends of which are bent over as at 31 and 32. Since the body 25 is other than cylindrical in cross section and will be placed in a broached hole in the lug, it will be unnecessary to provide a key and keyway. Moreover, the bent over portions 31 and 32 engaging upper and lower surfaces of the hole will confine movement of the engagement element to a direction substantially normal to the longitudinal axis of the body 25. It will be understood that a hole, rectangular in cross section, will be broached in the lug in a position contiguous to the shank receiving perforation, the arrangement being such that the nose 2.8 of the engagement element will project into the shank receiving perforation.

FIGS. 11 and 12, wherein like parts have been given like index numerals, are similar to FIG. and illustrate slightly modified forms of engagement elements. The engagement elements of FIG. 11 differ from that of FIG. 10 only in that the rearwardmost edges 31a and 32a of the portions 31 and 32 respectively are bent inwardly in a manner similar to the portions 9 and 10 of the engagement element 8 of FIGS. 1 and 2.

In the embodiment shown in FIG. 12, the upper and lower extensions 29a and 30a, on either side of the engagement nose 27, do not extend to the upper and lower surfaces of the body 25. The bent over portions 31b and 32b extend into the body 25 as shown.

The nose portions of the engagement elements of FIGS. 11 and 12 may be relieved, as described with respect to FIG. 10, to permit the retaining means to be driven into position in the transverse hole of a lug. The engagement elements of FIGS. 10-12 may be made by simple stamping or forming operations as described with respect to the engagement element of FIGS. 1 and 2.

A cage of the type described in the aforementioned U.S'. Letters Patent No. 3,057,609 may be applied to any of the previously described embodiments. For purposes of an exemplary showing, FIG. 13 (in which like parts have been given like index numerals) shows how such a cage may be employed with the retaining means of FIGS. 1 and 2. The cage has front portions (not shown) which are embedded in the front portion of the body 1. It has enlarged end portions, one of which is shown at 33, and it has a longitudinal rear portion 34 which lies outside the surface of the resilient body 1 and takes the place of the key 3. The cage is preferably a unitary metal structure which may be made by stamping and bending. It has the advantage of restricting permanent endwise distortion of the resilient body 1 and of providing a more positive key.

FIGS. 14 and 15 show another embodiment of the resilient retainer of the present invention. In this instance, a cylindrical resilient body 35, similar to the body 1 in FIG. 1, is provided with a central depression 36 having a flat surface 37. An engagement element 38 is aflixed to the surface 37 in any suitable manner. While it is within the scope of the invention to provide an engagement element similar to that shown in FIGS. 4 and 5, for purposes of an exemplary showing, the engagement element is illustrated as being similar to that shown in FIG. 12. The engagement element 38 has an engagement nose 39, upper and lower extended portions 40 and 41, and bent over portions 42 and 43. The bent over portions 42 and 43 are embedded in the resilient body 35.

The body 35 may be provided with a longitudinally extending key. The key may be an integral one of the type shown in FIGS. 1 and 2, or it may constitute part of a backing element of the type described with respect to FIG. 6. For purposes of an exemplary showing, the resilient retainer of FIG. 14 is illustrated as being provided with a cage of the type described with respect to FIG. 13. The cage has front portions 44 and 45 embedded in the body 35, enlarged end portions (one of which is shown at 46), and a longitudinally extending rear portion 47 serving as a key.

FIGS. 16 and 17 illustrate yet another embodiment of the present invention. In this instance, the resilient retainer comprises a cylindrical resilient body 48 and an engagement element 49 in the form of a plunger. The rearward end 50 of the plunger is enlarged and is embedded in the resilient body 48. The forward end 51 of the plunger 49 is adapted to extend into the shank receiving perforation of a11 lulg and to cooperate with a notch in a cutter bit s an The resilient body 48 may be provided vtu'th a key of the types described with respect to FIGS. 1, 4 and 6, or with a cage of the type described with respect to FIG. 13 or 14. It is also within the scope of the invention to provide the body 48 with a cylindrical sheath 52. of suitable material such as metal or the like. The sheath 52 may have an integral key 53 formed therein and a perforation 54 through which the end 51 of the plunger 49 extends.

While all of the engagement elements above described are preferably made of metal or the like by simple stamping or forming operations, it is within the scope of the present invention to cast them of metal or suitably durable substance. For purposes of an exemplary showing, FIG. 18 illustrates a cast engagement element similar to that shown in FIGS. 1 and 2. (like parts having been given like index numerals).

In FIG. 19 there is shown a lug having a body 56, lower extensions 57 and 58 and a perforation 38 for receiving the shank of a cutter bit. The lug as thus far described is conventional and is such a lug as may be employed as part of a mining machine cutter chain or welded to the cutter heads of mining machines. The lug of FIG. 19 is shown as having a transverse hole 60 which slightly intersects the shank receiving perforation. A rear keyway 61 is broached in connection with the hole 60; and the lug of FIG. 19 is capable of receiving any of the resilient retainers shown in FIGS. 16, 14 and 15. When the resilient retainer of FIGS. 14 and 15 is used, the retainer surface 37 should be substantially coplanar with the surface 59a of the shank receiving perforation 59. When resilient retainers of the type shown in FIGS. 1-6 are used, the intersection of hole 60 and perforation 59 need only be enough to permit the nose of the engagement means to extend into the perforation 59 by an amount sufficient to insure proper engagement of the nose with the notch in the cutter bit shank.

In FIG. 20 where like parts have been given like index numerals, the transverse hole 60a is so formed in the lug body that it neither intersects nor lies tangent to the perforation 9. Thus it becomes necessary to open up a passageway between the hole 60a and the perforation 59. This may be accomplished by drilling a transverse hole 62 through from the rear face of the lug so as to provide a passageway 63 between the hole 60a and the perforation. The hole 60a may be broached so as to enlarge it and the passageway 63 to a horizontal dimension equal or substantially equal to side thickness of the perforation 59. The nose of the engagement means should be long enough to pass through the passageway 63 and enter the perforation 59 so as to engage in the notch of a cutter bit shank therein. But the passageway 63 need not have a vertical dimension substantially greater than the vertical dimension of the engagement nose. It will be evident that when this is done, deflection of the engagement means will be substantially confined to a movement normal to the axis of a retaining means located in the hole 60a. The lug shown in FIG. 20 may be used with any of the retaining means of FIGS. l-6, 16 and 17. It will be understood by one skilled in the art that should the hole 60a be made square in cross section, the resilient retainer of FIGS. -12 may be used. If the hole 60a is made tangent to the shank receiving perforation 59, any of the resilient retaining means of FIGS. 1-6, 10-12 (if hole 60a is squared), 16 and 17 may be used provided the opening between the hole 60a and the perforation 59 is enlarged when necessary to permit sufficient extension of the engagement nose into the perforation 59.

In FIG. 21, the transverse hole 601) is shown as substantially tangent to the shank receiving perforation 59; but in this instance the forwardly extending keyway 61b serves to open up the hole 60b to the perforation 5 9 and to permit the nose of the engagement means to extend into the shank receiving perforation. The lug structure shown in FIG. 21 is especially adapted for the use of the retainers of FIGS. 7 and 8.

Modifications may be made in the invention without departing from the spirit of it.

The embodiments of the invention in which an excluiive property or privilege is claimed are defined as folows:

1. A resilient retainer for mounting the shank of a cutter bit for mining machine and the like in the shank receiving perforation of a lug of the type having a transverse hole for the receipt of said retainer, comprising an elongated body of resilient rubbery substance and an engagement means aflixed thereto and located substantially centrally of the long dimension thereof, said engagement means comprising a nose portion extending beyond an exterior surface of said body and outlying portions following and substantially coplanar with said last mentioned exterior surface of said body, said engagement means having a pair of rearward extensions embedded in said body.

2. The structure claimed in claim 1 wherein said body is cylindrical, said exterior surface beyond which said nose portion extends comprising a peripheral surface of said cylindrical body.

3. The structure claimed in claim 1 wherein said engagement means has a width less than the width of said shank receiving perfortaion of said lug.

4. The structure claimed in claim 1 including a key in association with said resilient body and extending longitudinally thereof.

5. The structure claimed in claim 1 wherein said body is substantially rectangular in cross section.

6. The structure claimed in claim 1 including a cage having end portions, front portions substantially in alignment with said nose of said engagement means and embedded in said body, and a rear connecting portion extending beyond the periphery of said body and serving as a key.

7. The structure claimed in claim 1 in which said body has key portions formed on the front side thereof and substantially in alignment with said nose.

8. The structure claimed in claim 1 wherein said nose portion is relieved at its ends.

9. The structure claimed in claim 1 wherein said extensions are hook-shaped.

10. The stmcture claimed in claim 1 in which a key is associated with said body, said body being substantially cylindrical in configuration.

11. The structure. claimed in claim 10 wherein said body has a semi-cii cular casing of sheet metal on the side opposite said engagement means, said key being formed on said casing.

12. The structure claimed in claim 1 wherein the said rearward extensions are directed toward each other whereby to anchor said engagement means in said body.

13. The structure claimed in claim 1 wherein said body has a centrally located depression therein, said depression having a substantially planar surface parallel to the long axis of said body, said planar surface comprising said surface beyond which said nose portion extends.

14. A resilient retainer for mounting the shank of a cutter bit for a mining machine and the like in the shank receiving perforation of a lug of the type having a transverse hole for the receipt of said retainer, comprising an elongated substantially cylindrical body of resilient rub bery substance and an engagement means aflixed thereto and located substantially centrally of the axis thereof, said engagement means comprising a cylindrical plunger the axis of which is perpendicular to the axis of said resilient body, one end of said plunger being enlarged and being embedded in said body, the other end of said plunger being rounded and comprising a nose portion extending beyond an exterior surface of said body.

15. The structure claimed in claim 12 including a cy lindrical metallic sheath surrounding said resilient body, said sheath having a perforation through which said nose portion extends, said sheath having a key formed therein and extending longitudinally thereof.

16. A lug member having a metallic body with a shank receiving perforation formed therein, said body having a hole extending through the lug transverse the axis of :said perforation and formed in the metal of the body of said lug off side the said perforation, the said hole having a coextensive keyway formed in connection with it on the side adjacent said perforation, said keyway intersecting said perforation and forming the sole interconnection between said hole and said perforation.

17. The structure claimed in claim 14 including a resilient retainer comprising an elongated body of resilient rubbery substance and an engagement means affixed thereto and located substantially centrally of the long dimension thereof, said engagement means comprising a nose portion extending beyond an exterior surface of said body, said nose portion having a width less than the width of said shank receiving perforation, said resilient body having key portions formed thereon, said key portions being substantially in alignment with said nose, said resilient body lying within said transverse hole, said key portions of said body lying in said keyway, said nose portion extending into said shank receiving perforation.

18. A lug comprising a metallic body having a shank receiving perforation therein and having a first hole formed through said body, the axes of said first hole and said perforation lying substantially at 90 to each other, said hole being formed so that its inside surface is spaced from the adjacent inside surface of said perforation, and a second hole formed in said body with an axis substantially perpendicular to the axes both of said perforation and of said first hole, a portion of the said second hole forming the sole interconnecting passageway between said first hole and said perforation.

19. The structure claimed in claim 16 including a resilient retainer comprising an elongated body of resilient rubbery substance and an engagement means affixed thereto and located substantially centrally of the long di mension thereof, said engagement means comprising a nose portion extending beyond an exterior surface of .said resilient body and having a Width less than the width of said shank receiving perforation, said resilient body lying within said first hole with said nose portion projecting into said shank receiving perforation through said passageway formed by said second hole.

References Cited UNITED STATES PATENTS US. Cl. XJR. 37-142; 858.3 

